Ever since we had a new solid fuel heating system installed 18 months ago we've had a constant problem with the overflow from the top of the hot water tank.
System is gravity fed so hot water tank is in the loft direct above the back boiler and fed by a header tank.
We've now had 3 different plumbers come out (and charge cold hard cash) and none of them have sorted the problem (or come back when asked to take a 2nd look!) :
No 1. said it was the ballcock and stripped it down and replaced.
No. 2 said it was the valve mechanism so this was replaced.
No. 3 said it was the ballcock again and replaced with a new one. Problem still not solved.
When I go up into the loft the ball cock and valve seem to be working fine. The water still rises above the ball cock.
A plumber on a different forum said it might be water pressure but we live 800 feet above sea level in Scotland and if anything our pressure is lower than average.
Its got to the stage where we are looking at running a pipe from the overflow pipe (outside) to the nearest drainpipe (in fact if anyone here has intstructions for that that would be great (failing a solution to the original issue)).
Apologies for the long read.